“To help explain the difference between “individual” and “person”, the model of the Holy Trinity is useful…”
To help explain the difference between “individual” and “person”, the model of the Holy Trinity is useful because it establishes a truth beyond the regular meaning of secular philosophical concepts. Two of the key terms in trinitarian theology are ousia and hypostasis; essence (nature) and subsistence (person). Just to confuse things, even in Greek, these two terms can be used as synonyms.
In terms of trinitarian doctrine, Vladimir Lossky explains to us in his book, In the Image and Likeness of God, that “… according to the doctrine of the Fathers, there is between ousia and hypostasis the same difference as between the common and the particular…”. Lossky continues his line of thinking with a complex thought, “The hypostasis is the same as ousia; it receives all the same attributes – or all the negations – which can be formulated on the subject of “superessence”; but it nonetheless remains irreducible to the ousia.”
Lossky tells us that the church Fathers of the fourth century worked diligently to develop and articulate a complete theology of the Holy Trinity. This was especially true of three men who became known as the Cappadocian Fathers (St. Basil the Great, St. Gregory of Nazianzus, and St. Gregory of Nyssa). They struggled mightily to articulate and differentiate between theological terms like hypostasis and ousia: “It was a great terminological discovery to introduce a distinction between the two synonyms, in order to express the irreducibility of the hypostasis to the ousia and of the person to the essence, without, however, opposing them as two different realities. This will enable St. Gregory of Nazianzus to say, ‘The Son is not the Father, because there is only one Father, but He is what the Father is; the Holy Spirit, although He proceeds from God, is not the Son, because there is only one Only Begotten Son, but He is what the Son is’ (Or. 31, 9)”